WhatsApp would stop working on several Android and iOS devices starting February 1, 2020. The messaging app, on its website, had previously announced that it would be dropping support for older versions of Android and iOS smartphones. WhatsApp ended support for Windows Phone OS on December 31, 2019.
WhatsApp users on Android and iOS need to update their smartphones to continue using the messaging app. The FAQ page states that smartphones running on Android version 4.0.3 and iOS 9 and later will continue to be able to use WhatsApp.
This means that if your smartphone runs on the older operating system than the ones mentioned above, you need to upgrade to the latest version to continue using WhatsApp from February 1, 2020.
For iOS, users need to ensure that their iPhone is updated to iOS 9 or later for using WhatsApp. The support page reads, “On iOS 8, you can no longer create new accounts or reverify existing accounts. If WhatsApp is currently active on your iOS 8 device, you’ll be able to use it until February 1, 2020.”